1. Field of the Invention
The present invention relates to a device provided to a disk drive for chucking a disk, and more particularly to a disk-chucking device of a disk drive designed to reduce deviation of force between spring members transmitted to a disk through chuck pins, thereby enhancing a centering performance of matching the center of the disk to the rotational center of a motor.
2. Description of the Related Art
Generally, a disk drive comprises a deck base constituting a body of the disk drive, a loading-unloading means for loading or unloading the disk on the deck base, a rotation-driving means for rotating the disk loaded by the loading-unloading means at a predetermined velocity, and a recording and/or reproducing means for recording and/or reproducing information on a recording surface of the disk while being moved in a radial direction of the disk rotated by the rotation means. Here, the disk can be loaded or unloaded in a state of being mounted on a tray or can be inserted into or withdrawn from an interior of the deck base in a state of being received in a caddy or a cartridge by various types of disk drive known in the prior art.
Typically, as for the rotation-driving means, a spindle motor is employed to rotate the disk, and as for the recording and/or reproducing means, an optical pick-up unit is employed.
FIG. 1 is a plan view illustrating a disk drive with a general disk-chucking device, and FIG. 2 is a cross-sectional view illustrating the disk drive with the general disk-chucking device. Referring to FIGS. 1 and 2, the disk drive 1 comprises a disk-chucking device 10 for chucking a disk, to be rotated, on the top surface of a substrate 31 having an integrated circuit chip 32 and a plurality of connectors 33 and 34 mounted thereon, and a spindle motor 20 for supplying a rotational driving force.
The disk-chucking device 10 provided to the disk drive 1 acts to maintain stability of the disk rotated in one direction by virtue of the rotational driving force of the spindle motor 20 while fixing the disk such that the center of the disk is matched to the rotational center of the motor. Thus, chucking performance of the disk-chucking device 10 is very important in the field of disk-chucking devices.
As shown in FIGS. 1 and 2, the disk-chucking device 10 is integrally equipped with a rotor case 24 of the spindle motor 20, which comprises a stator 20a with one or more coils 21 wound around a yoke 22 and a rotor 20b having a magnet 25 at a location corresponding to the coils 21. The rotor case 24 is provided, on an upper surface thereof, with a chuck base 12, which has a plurality of arranging parts 12a cut in a radial direction along an outer peripheral surface of an upper surface of the chuck base 12, and allows a central void of the disk to be inserted thereon.
A plurality of chuck pins 13 are assembled to the arranging parts 12a so that they are linearly moved along the arranging parts 12a, and are elastically and forwardly supported by virtue of an elastic force of spring members 15, respectively. Elastic pieces 14 are arranged between the arranging parts 12a of the chuck base 12 to elastically support the central void of the disk inserted into the chuck base 12 with a self-retaining elastic force of the elastic pieces 14.
In FIGS. 1 and 2, reference numeral 16 indicates a rubber material contacting a lower surface of the disk, reference numeral 23 indicates a holder for holding the yoke 22, reference numeral 26 indicates a shaft for supporting rotation of the rotor 20b against the stator 20a, reference numeral 27 indicates a bearing member, reference numeral 28 indicates a plate to close an opened lower step of the holder 23, and reference numeral 29 indicates a hall element.
According to a method of inserting and fixing the disk using a conventional disk-chucking device 10 with such a construction as described above, when the disk is vertically pushed down through the chuck base 12 from above, a lower end edge of an inner peripheral surface of the central void contacts the chuck pins 13 by way of interference with the chuck pins 13, since the chuck base 12 has an outer diameter lower than an inner diameter of the central void of the disk and each of the chuck pins 13 assembled to the chuck base 12 has a leading end extending in the direction of an outer periphery of the chuck base 12.
Here, each of the chuck pins 13 has an upper surface of the leading end gently and downwardly tapered. Accordingly, by virtue of a mounting force vertically applied to the chuck pins 13 from the disk, the chuck pins 13 are pushed backwardly while compressing the spring members 15, and the elastic members 14 are also pushed backwardly and then deformed.
Then, when the disk contacts the ring-shaped rubber material 16 mounted on the upper surface of the rotor case 24, the disk is chucked to the chuck base 12 so as to maintain a state of being inserted into the chuck base 12 by means of the plurality of chuck pins 13 tending to return to their initial locations by virtue of an elastic restoration force generated upon compression of the spring members 15.
Furthermore, the elastic pieces 14, provided between the chuck pins 13 such that the outer diameter of the elastic pieces 14, formed by drawing a line connecting the outer peripheral surfaces of the elastic pieces 14, is larger than the inner diameter of the inner peripheral surface of the central void of the disk, uniformly and elastically support the inner peripheral surface of the central void of the disk chucked by the chuck base 12 in the radial direction. Thus, the center of the disk can be matched to the rotational center of the spindle motor 20 by means of the elastic pieces 14.
Meanwhile, a force required for inserting and fixing the disk into the chuck base 12 of the disk-chucking device 10 is determined depending on the elastic force of the spring members 15 consistently supporting the chuck pins 13 forwardly. With regard to this, it is desirable that the spring members 15 respectively provided to the chuck pins 13 provide the identical elastic forces. However, in view of the process of manufacturing the spring members 15, it is difficult to practically produce spring members having identical elastic forces. Additionally, the spring members 15 are designed to have an elastic force higher than that of the elastic pieces 14.
Accordingly, in the case where the elastic force is applied excessively only to some of the chuck pins 13 due to disproportionate elastic force of the spring members 15 elastically supporting three or more chuck pins 13 provided to the chuck base 12, the disk is biased toward one side, where the elastic force of the spring members 14 is applied relatively excessively within a space defined between the inner peripheral surface of the central void of the disk and an outer peripheral surface of the chuck base 12, thereby causing eccentricity by which the center of the disk is not matched to the rotational center of the spindle motor 20 and thus deviates to one side.
Additionally, in case of a large eccentricity causing the center of the disk to be deviated from the rotational center of the spindle motor and biased to one side, the probability of error is increased when reading data on the disk or recording data on the disk using the optical pick-up unit, thereby impeding accurate and smooth operation of the recording and/or reproducing of the data on a recording surface of the disk.
Additionally, a moving distance of the optical pick-up unit is also increased by the degree of eccentricity, thereby increasing energy consumption for moving the optical pick-up unit, and lowering life span of the disk drive.